Gambusia sexing

The main difference between male and female gambusia is the same as for many livebearers, the shape of the pelvic fin. In the male the fin is longer and pointed, in the female it is shorter and more rounded. The male pelvic fin is referred to as the gonopodium and is used to tranfer sperm to the female.

Fry Watch

10/20/09
I have at least six new fry. The are either black bar endlers or gambusia, only time will tell.

11/2/09
After vanishing for most of the intervening period, 2 of the fry reappeared near the water surface yesterday. This pattern of behavior and their evolving appearance suggests that they are gambusia. Currently they have vanished again.

11/4/09
I saw three fry yesterday, but could only find this one today. Definitely looking like a gambusia, no signed of spotting so they are either female or not melanistic.

11/28/09
The fry are large enough to distinguish make and female based on fin shape. So far they all seem to be standard gambusia. I am separating males and females now to prevent over-population.

Spot

"Mosquito fish" is a common name used to refer to several small American Gambusia species, sometime introduced to ponds to control mosquito larvae. These three are Gambusia affisni holborooki.

The male, Spot, has his distinctive piebald coloration because he has melanistic spotting. This is a naturally occurring Y-linked mutation, meaning it only affects males. It also doesn't breed true, so some offspring of melanistic males are gray colored.